[outworlder]

> If you end up subnetting down into small subnets to give customers

Since this is about AWS... they don't do that. They will assign a random IP out of their available public IP for every resource that needs an IP. For many of these you can allocate an IP and move it around if you want (that's why they call it 'Elastic IPs').

Unless you have special needs (and actually own the IP ranges) your VPCs will all be in a private IP range. You can even have multiple VPCs with the same range with zero issues (unless you want to peer them).